BEIRUT — Two suicide bombers killed the top Al Qaeda operative in Syria on Sunday, blowing themselves up inside the militant leader’s compound in the northern city of Aleppo, rebels and activists said.
The killing of Abu Khaled al-Suri, who rebels said was serving as Al Qaeda leader Ayman al-Zawahri’s representative in Syria, occurred at a time of bloody rebel infighting between a Qaeda-breakaway group known as the Islamic State of Iraq and the Levant and an array of ultraconservative and more moderate opposition fighters.
There was no immediate claim of responsibility for Sunday’s assassination, but rebels quickly accused the Islamic State. Suri had been critical of the group, reportedly blaming it for the internecine conflict among rebels that has killed thousands of people across northern Syria since it began in early January.
If an Islamic State role in Suri’s death is confirmed, it could further complicate efforts to resolve the infighting, which has undermined rebel efforts to oust President Bashar Assad in Syria’s nearly three-year civil war.
Since the rebel-on-rebel clashes began, government forces have chipped away at opposition-held areas, including around Aleppo.
A native Syrian with longstanding ties to Al Qaeda, Suri was a cofounder of Ahrar al-Sham, a prominent, hard-line group in Syria that is part of a powerful alliance known as the Islamic Front.
Akram al-Halabi, a spokesman for the Islamic Front, described Suri as ‘‘a big figure in global jihad,’’ saying he was appointed by Zawahri last year to mediate a dispute between the two Al Qaeda affiliates in Syria: the Islamic State and the Nusra Front.
Speaking via Skype, Halabi said Suri had criticized the Islamic State for its antagonistic approach toward other rebel factions. He said rebels believe the Islamic State, which Al Qaeda publicly disowned earlier this month, was behind Sunday’s bombing.
‘‘The first fingers of blame point to the State,’’ Halabi said. ‘‘Unfortunately this is going to make the infighting worse.’’
He did not provide any evidence to support his assertion.
The Britain-based Syrian Observatory for Human Rights said two others were also killed in the attack, which it attributed to the Islamic State. The Observatory obtains its information from a network of activists on the ground.
Suri had long been on the radar of Western intelligence agencies. In 2002, Spanish officials described Suri, whose real name is Mohamed Bahaiah, as the courier for the late terrorist leader Osama bin Laden between Afghanistan and Europe.
Islamic extremists have emerged as a powerful force in Syria’s civil war. The rise to prominence of hard-line militants such as Suri has dampened the enthusiasm among Western leaders for the anti-Assad opposition.
Charles Lister, an analyst with the Brookings Doha Center, said Suri’s activities in Syria had been a concern for the United States and its allies.
‘‘He is essentially a core Al Qaeda veteran who almost certainly . . . had extensive, close relations with [Osama] bin Laden,’’ and other senior leaders, Lister said. ‘‘The fact that he had such a high position in Ahrar al-Sham, and confirmed it himself, his Al Qaeda history — it made elements in the US administration potentially consider Ahrar al-Sham as a terrorist organization.’’
Syria’s uprising began with largely peaceful protests in March 2011 before turning into a civil war that has killed more than 140,000 people. The conflict has also forced 2.5 million to flee the country, left millions more in desperate need of aid, and caused immense suffering across the nation.
On Saturday, the United Nations Security Council passed a resolution demanding immediate access everywhere in Syria for humanitarian aid. The resolution, which marked a rare instance of unity on the Security Council, doesn’t threaten sanctions but it does express the council’s intention to take ‘‘further steps’’ if the resolution isn’t implemented.
Syria’s Foreign Ministry on Sunday welcomed the resolution and voiced its readiness to cooperate but said that the top priority must be respecting national sovereignty. It also said that to address the humanitarian crisis demanded dealing with ‘‘foreign-backed terrorism.’’
Damascus says the crisis in the country is caused by an international conspiracy against Syria.
Also Sunday, a car bomb exploded near a charity field hospital close to the Turkish border, wounding mostly medics and patients who had fled violence elsewhere in the country, activists and Turkish media said.
Turkish ambulance crews evacuated at least 11 of the wounded, including a baby, to Turkey, said Syrian activists of the Idlib News group.
Zidane Zenglow, a journalist working for the pan-Arab al-Arabiya network, said at least one person was killed in the blast — a young girl, his cousin.